Search

The phylogenetic affiliations of organisms responsible for aerobic CO oxidation in hypersaline soils and sediments were assessed using media containing 3.8 M NaCl. CO-oxidizing strains of the euryarchaeotes, Haloarcula, Halorubrum, Haloterrigena and Natronorubrum, were isolated from the Bonneville Salt Flats (UT) and Atacama Desert salterns (Chile). A halophilic euryarchaeote, Haloferax strain Mke2.3(T), was isolated from Hawai'i Island saline cinders. Haloferax strain Mke2.3(T) was most closely related to Haloferax larsenii JCM 13917(T) (97.0% 16S rRNA sequence identity). It grew with a limited range of substrates, and oxidized CO at a headspace concentration of 0.1%. However, it did not grow with CO as a sole carbon and energy source. Its ability to oxidize CO, its polar lipid composition, substrate utilization and numerous other traits distinguished it from H. larsenii JCM 13917(T), and supported designation of the novel isolate as Haloferax namakaokahaiae Mke2.3(T), sp. nov (= DSM 29988, = LMG 29162). CO oxidation was also documented for 'Natronorubrum thiooxidans' HG1 (Sorokin, Tourova and Muyzer 2005), N. bangense (Xu, Zhou and Tian 1999) and N. sulfidifaciens AD2(T) (Cui et al. 2007). Collectively, these results established a previously unsuspected capacity for extremely halophilic aerobic CO oxidation, and indicated that the trait might be widespread among the Halobacteriaceae, and occur in a wide range of hypersaline habitats., (© FEMS 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Three strains of Gram-negative, aerobic, neutrophilic, extremely halophilic archaea, designated ZJ206(T), ZJ203 and ZJ204, were isolated from a solar saltern in Zhe-Jiang Province, China. Phenotypically and on the basis of 16S rRNA gene sequences, the strains were very similar. Comparative 16S rRNA gene analysis revealed 96.4-97.4 % sequence similarity to members of the genus Haloferax. The major polar lipids were C(20)C(20) derivatives of phosphatidylglycerol, phosphatidylglycerol phosphate methyl ester, diglycosyl glycerol diether and sulfated diglycosyl diether. The DNA G+C content of strain ZJ206(T) was 62.2 mol%. The results of DNA-DNA hybridizations and physiological and biochemical tests allowed genotypic and phenotypic differentiation of the isolates from closely related species. Therefore the isolates should be classified as members of a novel species, for which the name Haloferax larsenii sp. nov. is proposed. The type strain is ZJ206(T) (=CGMCC 1.5347(T)=JCM 13917(T)).